Radio Frequency Identification (RFID) and the Lean Construction Process

Taylor, J. M.

Auburn University

(email: taylojt@auburn.edu)

Abstract

The demand for increasing efficiency in project delivery has stimulated the exploration of new

technologies which may be implemented to improve productivity of construction work. One

particular technology that has recently drawn the attention of the industry is Radio Frequency

Identification (RFID) and its possible applications within the construction arena. RFID technology

as applied to the construction industry is still in its infancy. While building on past successes, as

revealed in the limited number of research studies, exploration of new uses continues. There are,

obviously, many uses for RFID technology in the construction arena. Each of these uses is aimed at

utilizing ones resources in a more efficient manner and streamlining the project management process.

Some of the uses are (1) personnel tracking and safety, (2) material handling and yard management,

(3) tool or equipment tracking, (4) theft deterrence, and (5) integration with BIM.

The purpose of this study is to explore the different uses of RFID technology in the construction

industry and how these integrate with the Lean Construction Process. The case study methodology

will be utilized to investigate how contractors are beginning to utilize the technology to increase

efficiencies within the industry. By analyzing actual contractor’s use of this technology through the

case study method, the industry will become more and more aware of and familiar with the

technology, its applications and projected benefits.

Keywords: radio frequency identification, RFID, lean construction, technology, construction

technology

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1. Introduction

Radio Frequency Identification (RFID) is not a new technology. Its use dates back as early as World

War II when it was used for friend or foe recognition for anti-aircraft gunmen. RFID is a versatile

technology and is put to a wide variety of uses, such as security for retail stores, tracking transfer

bags at airports, managing inventory and theft in manufacturing plants, electronic cashless payment

cards, and electronic car keys (ERA Build, 2006). Its use has become so prevalent that some

speculate that RFID will universally replace barcodes in the not too distant future (Hock, 2009). The

use of RFID technology is slowly creeping into the construction industry as an innovative tool in

supply chain and inventory management. Its adoption and implementation into a historically

obstinate American construction industry has been slow, but as prices on tags continue to fall (as low

as 5 cents) it is reasonable to expect that the industry will begin to take advantage of all that Radio

Frequency technology has to offer (ERA Build, 2006).

Lean construction or Lean Project Delivery (LPD) is an innovative planning, design, and operational

philosophy. It has been championed by co-founders of the Lean Construction Institute, Gregory

Howell and Glenn Ballard, since the early 1990s (Post, 2007; ENR, 2007). Lean construction was

inspired by lean production methods developed by Japanese automotive manufacturer, Toyota. The

lean production initiative was headed by engineer Taiichi Ohno whose pioneering methods were

primarily concerned with the elimination of waste and inventories. He was a student of Henry Ford,

but saw too much waste in his operations and focused on perfecting the design of the production

system; thereby decreasing defects and the need for re-work. Ohno disagreed with the production at

all costs mindset and empowered his workers to make decisions (even stopping the assembly line

upon receipt of a defect) requiring less management personnel. Lean production consist of four basic

principles which have been modified and applied to the construction industry: (1) identify and

deliver value to the customer, eliminate anything that doesn’t add value; (2) organize production as a

continuous flow; (3) perfect the product and create reliable flow through stopping the line, pulling

inventory, and distributing information and decision making; and (4) pursue perfection (Howell

1999).

2. Background of the problem

The construction industry is based on firms’ ability to constantly improve efficiency and productivity

in order to survive in a competitive environment. New techniques and methods are constantly crafted

and applied to the industry, from better equipment and machinery to highly detailed scheduling

software. Lean Construction principles and Radio Frequency Identification are two such innovations

and can vastly improve operational efficiency and productivity (Park, 2005).

Radio Frequency Identification (RFID) technology is an automatic identification technology that

utilizes radio frequencies to transmit data. RFID involves the use of tags, also called transponders,

which contain a portable, modifiable database which is capable of receiving data from and

transmitting data back to a reader. Radio Frequency Identification is a sister technology to bar code

labels and scanners. Bar code labelling is often seen in use on construction sites as well, but RFID is

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now performing some of the same tasks (Jaselskis & El-Misalami, 2003). Some predict that bar code

technology will soon be obsolete (Mokhoff, 2008). RFID tags are able to withstand harsh treatment

and environments and are now cheaper than ever with some priced as low as five cents (ERA Build,

2006; Atlas RFID, 2009). Due to their becoming more durable and cheaper over the last decade it is

expected that RFID technology will quickly become more prevalent in the construction industry

(Anderson, et al., 1995). RFID tags can be placed on any resource and track it throughout the entire

construction process.

Lean construction is a production management-based approach to project delivery that focuses on

maximizing value and minimizing waste through collaboration and teamwork in job planning, design,

and management (Ballard & Howell 2007). The lean philosophy can be applied to any type of

construction, but it is particularly useful on complex, uncertain and quick projects. It challenges the

belief that there must always be a trade between time, cost, and quality (Howell, 1999). Lean

construction encourages teamwork and a willingness to shift burdens along the supply chain. The

problem with the current method of job design, planning, and management is that production systems

do not operate well when every person tries to optimize their performance without understanding how

their particular job affects the rest of the activities on-site. The current method focuses on speed of

production at all costs. Lean construction focuses on managing dependencies and variation in

production rates and supply of materials throughout the production system. Managers can minimize

waste and maximize customer value through management of variation, dependencies, and backlogs;

thereby increasing productivity and efficiency (Ballard & Howell 2007).

3. Purpose of the study

The purpose of this study is to examine what strategies involving lean construction principles and

Radio Frequency Identification technology construction firms are employing to become more

efficient and productive. All construction firms are interested in gaining a competitive advantage

through efficiencies in cost and time. The findings of this study are meant to make the construction

industry, academic and non-academic, aware of methods that are improving the way the industry

operates (Coady, et al., 2008).

There is a general lack of academic literature incorporating both lean construction initiatives and

RFID technology (Coady, et al., 2008). Some studies have been written solely on the lean

construction principles and methods and some focus only on RFID technology. It would be

beneficial to the construction field to expose a range of issues and situations in which RFID and lean

construction philosophies can be applied to the industry. This study aims to combine the

technological and philosophical aspects of RFID and Lean to provide general contractors with ways

to increase productivity in their company operations.

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4. Lean construction

Lean construction has been in existence since the early 1990s when Gregory Howell and Glenn

Ballard became enamored with the lean philosophy that Toyota Motor Corporation used to gain a

competitive advantage in the automotive industry under engineer Taiichi Ohno (Post, 2007; ENR

Staff, 2007). Howell and Ballard converted Toyota’s manufacturing practices into a philosophy that

could be applied to the construction industry which they aptly dubbed lean construction (Howell,

1999).

Lean construction, in essence, is the process of minimizing waste through increased collaboration,

predictability, innovation, and accountability (Post, 2007). It includes contractors in the design

phase, which helps facilitate collaboration among the parties involved with the building process.

Therefore, questions can be asked and conflicts can be resolved before construction begins (ENR

Staff, 2007). Lean Production Design also focuses on the way the work itself is actually planned and

managed. If the planning system is under control, managers can control inventories and excess

capacities of labor and/or materials and avoid causing variation in work flow (Howell, 1999).

5. RFID

Radio Frequency Identification technology has been in use for over 70 years in a wide variety of

ways, but it has not been in use in the construction industry for long (ERA Build 2006). The oldest

literature found on RFID’s possible influence on the construction industry is journal article by

Anderson, Jahren, Rodriguez, and Njos titled Radio-Frequency Identification Applications in

Construction Industry written in 1995.

Radio Frequency Identification (RFID) is an automatic identification technology that utilizes radio

frequencies to transmit data. RFID involves the use of tags, also called transponders, which contain a

portable, modifiable database which is capable of receiving data from and transmitting data back to a

reader. The reader and the tag must be within a designed range of each other to operate properly

(Anderson, et al, 1995).

There are two distinct types of tags; passive and active. A passive tag is one that lacks a battery

supply and therefore must be activated by the emission of a specific frequency from a reader. Passive

tags have an unlimited life and are usually smaller, lighter, and cheaper than active tags, but also have

a shorter range or operable distance from the reader. Active tags are those which operate on a limited

battery supply and intermittently emit a frequency to be interpreted by a reader. Active tags have

longer reading ranges and can store more data, but are relatively large, heavy, and expensive

compared to passive tags (Taylor et al., 2009). Passive tags have a shorter reading range than active

ones because they operate on a lower frequency. As the operational frequency of the device

increases, the distance at which the tag can be read increases and so does the speed with which the

information will be exchanged between the tag and the reader. A low frequency tag operates at

around 120-135 kHz and an extremely high frequency tag operates at about 2450 MHz (Taylor et al.,

2009).

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The applications of RFID in the construction industry continue to expand. Active tags have been cast

in concrete to monitor the temperature of the mix and provide workers real-time temperature

readings, which aids in monitoring the curing process (Gaudin, 2008). Some within the industry are

tagging job-site equipment with high-frequency active tags in order to monitor its location, deter theft

and locate equipment should it be stolen (Gaudin, 2008). Worker identification cards can be loaded

with passive tags so that management can monitor an employee’s location on site. There is also

evidence to support the idea that an employee’s productivity can be determined, to a degree, by their

location on the jobsite throughout the workday (Jaselskis & El-Misalami, 2003). RFID technology

can be implemented to record on-site inventory as it arrives, document where and when it was

received, and locate specific items electronically as they are being installed (Taylor et al., 2009).

6. Case study

This specific case study pertaining to RFID applications within the construction industry was

performed on a power plant expansion project constructed by Bechtel Corporation in the Northern

United States. The expansion project consists of two coal-fired steam-turbine generating units, as

well as supporting facilities, and related civil work. The contractor’s scope of work consists of

engineering, procurement, construction, and start up. The project will cost an estimated $2.15 billion

dollars, with construction scheduled from 2005 to 2010. Of the two units, one is scheduled to begin

operation in 2009, and the second is scheduled to begin operation in 2010.

6.1 Materials management process without RFID

The materials management process for the project is comprised of a series of activities or processes

that ultimately lead to the installation of a component into the facility. A majority of the steel and

piping for the project was received on site via truck. Some components for the project were shipped

by boat. Materials are delivered to the site along with a packing slip, which details the material item,

where it came from, contact information, date of shipment, etc. Each material component comes with

its own specific material identification code for the project that is written on the surface of the

component. The entire receipt process and the entry of items into the materials management database

was performed with a paper based manual method. The materials are accounted for and manually

entered into the materials management database system, so that construction activities could be

coordinated depending on the availability of materials.

As material components arrive at the job-site, they are taken to the lay-down yards and placed within

a specific grid. Caldas et al. refer to this stage as “Sorting” (Caldas, et al, 2006). The components

are grouped within grids according to characteristics and material identification code. Different

groups of materials are assigned a color scheme. Specific colors and twisted combinations of colored

flags are attached to the respective groups of materials for future identification and locating purposes.

Materials are stored in the lay-down yard until needed for installation. When a construction crew or

trade is prepared to construct a certain portion of the facility, the necessary materials have to be

retrieved from the lay-down yard. For this, a superintendent coordinates with a field engineer and

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communicates the plans for assembling a certain area of the facility. The field engineer would

generate a material withdrawal request (MWR), which listed all of the necessary materials that the

superintendent’s crew needed in order to complete the specified scope of work. The MWR is sent to

the Materials Management staff, where they develop a “pick ticket”. The pick ticket lists the

materials needed, along with the respective lay-down yard and grid location of the component.

Workers would take the pick ticket to the lay-down yards and visually locate the materials that were

needed for installation. Once located, the components were flagged, organized, and staged so that the

pick-up process of those materials would be easier and more efficient. The materials would be

loaded and taken to the construction area where they were turned over to the construction team.

Once the materials had been turned over to the construction team, the receiving foremen would sign

off on the materials to assure that they have received them.

6.1.1 Problems presented with the manual system heading

The issues presented for materials management on Bechtel’s power plant expansion revolve around

the ability of personnel to locate and flag specific material items (flagging) so they can be organized

for convenient pick-up and transporting. When materials required for installation are not ready at the

time they are needed, installation crews become idle and non-productive, which can increase craft

labor hours up to 16 - 18% (Torrent and Caldas, 2009).

The sheer volume of materials required on the construction site presented the materials management

team with several problems. The $2.15 billion power-plant project is comprised of an incredibly

large number of intricate components of steel, piping, and other structural and functional

components. Individual piping pieces can become very difficult to identify when they are closely

stacked together in areas of what can be thousands of square meters per lay-down grid.

The arrangement of the material yards is also a factor which can contribute to decreased efficiency in

the flagging process, as well as the rest of the material management process. The farthest lay-down

yard was almost three miles from the construction site. Therefore, minimal time spent at the storage

yard was desired since it took a significant amount of travel time to get there and back.

Another factor affecting the material management process was the weather conditions. Extremely

cold temperatures, combined with rain and snowfall, were the main areas of concern regarding severe

weather that could affect construction productivity. The flagging process was made much more

difficult after heavy snowfalls for the obvious reason that the materials would get covered in snow

and the material ID codes must be uncovered, with shovels or by hand, in order to be properly

identified.

6.2 Experience with automated systems and lean construction

Due to the problems associated with the manual tracking system, the decision was made by

management to implement a full scale RFID/GPS based system for the entire on-site materials

management process. ERA Build noted that long implementation time and difficulty in obtaining the

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skills and knowledge on the technology can be key operational and technical barriers that face

companies in adopting the technology (ERA Build, 2006). This was the company’s first full scale

application of the technology. The decision to invest and employ the technology on a large scale was

made less difficult, in large part, due to the company’s previous participation and involvement in

pilot tests. Bechtel hosted an academic study pertaining to RFID technology on one of its

construction sites in 2005.

Bechtel’s field test was performed over approximately three months on a twin-boiler project in

Rockdale, Texas. Chief sponsors of the pilot were the Construction Industry Institute (CII) and

FIATECH, and the research team was comprised of about two dozen individuals representing

universities, construction firms, institutes, and technology vendors (Saywer, 2008). The field tests

compared the times of the typical paper based manual method of locating steel items, to the

RFID/GPS based automated method for tracking down components in the lay down yards. The trial

results found that the average time taken to locate a specific component with the manual process was

36.8 minutes. The average time taken to locate materials with the automated method was 4.6 minutes.

Also, when using the manual method, 9.52% of material components “were not immediately found,”

compared to the 0.54% of the automated method. The research team regarded the success rate of the

automated system to be quite significant considering the fact that the failure to locate critical items

can lead to costly slowdowns, and sometimes even re-procurement (Saywer, 2008).

6.2.1 Lean strategies

Bechtel utilizes Lean management strategies throughout their business processes and construction

projects. Lean aims to decrease the amount of defects, or errors, or failures that a company might

encounter throughout its business processes. Lean aims to develop quantifiable business

improvements via statistical analysis of data. The experience gained through the field study proved

to be valuable for Bechtel, in regards to developing future applications. Not only did the field studies

produce valuable data for statistical analyses, but the relationship that was gained with the technology

vendor during the field tests, was able to be continued, and developed into a business relationship for

their full scale implementation.

RFID technology fits well with the Lean production philosophy fulfilling all four of the goals

previously mentioned. Utilization of the RFID material tracking system allowed the integration of

the delivery, storage, stocking and supply processes through a single automated system thereby

providing the client with a more productive and efficient materials management system.

6.2.2 Technological specifications: Tags and readers

The tags utilized in this full scale implementation were active RFID tags. These active tags

continually “wake up” and send out their ID information at pre-configured intervals (i.e. every 1

second, every 2 seconds, every 10 seconds, etc.). The active tags are Ultra High Frequency (UHF),

and they operate on a 915MHz frequency level. The lifespan of the tags is generally five years. The

physical dimensions of the tags measure about 5 x 1 x .85 inches and weigh about 50 grams. Tags

with these characteristics and reading ranges cost approximately $25(US) each.

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The reading units utilized in this application were a combination of RFID reader and Global

Positioning System (GPS) receiver. The readers were mobile, handheld computers, or personal digital

assistants (PDA), suitable for field readings. The readers’ operate with Microsoft Windows.

Approximately six handheld readers were utilized on the entire project; usually a team (i.e. iron-

workers) would have its own reader which was designated for them each day. RFID/GPS readers

such as those utilized in this study currently cost approximately $5,000(US).

The automated materials management process also used barcode scanners for association purposes.

The scanners were mobile, handheld devices that utilize Bluetooth technology. The scanners operate

on High Frequency (HF) radio waves at a 13.56 MHz frequency level. The scanners are rechargeable.

The physical dimension of the barcode scanner is about 4.8 x 2 x 1.3 inches and weighs 132 grams

(about 0.3 pounds). These barcode scanners currently cost around $450-$500(US). Server software

is also required for the system and it cost approximately $35,000 - $50,000(US) depending on the

software and the vendor.

6.3 Implementing the RFID/GPS based system

The RFID/GPS based materials management process was not implemented from the beginning of the

project. It was only after the problems mentioned above arose, that the decision to implement the

automated tracking system was made. At that time, around 65-75% of the materials for construction

had already been delivered to the site. Having the majority of the materials on site meant that the

materials management process would have to be retro-fitted with the technology. Roughly 6-10

employees were assigned the task of attaching tags to materials in the lay down yards, and associating

those tags to the specific material piece in the management system. This project tagged 20,000+

unique material components with RFID tags. Approximately 12,000 tags were utilized for this

project, as tags are reusable.

6.3.1 Attaching and associating RFID tags to materials

RFID tags were attached to the material components with plastic zip ties. Once the tags are attached,

they must be associated with the respective material to which they are attached, for future tracking

purposes. Some materials arrived on site with a barcode label that indicated the component’s material

ID. Others did not have barcodes attached, and their material ID would be written on the exterior of

the component.

If the material component had been delivered with a barcode label, then the association process

becomes very simple and almost instant. The barcode label on the material component is simply

scanned along with the barcode label on the RFID tag attached to it. The barcode scanner is able to

instantly transmit the material ID and RFID tag’s ID into the RFID reading device wirelessly via

Bluetooth technology. Once the material ID and tag ID had been input into the RFID reader, the

worker could hit “associate” on the RFID reader to initiate communication with the tag while next to

it, and that specific RFID tag’s ID would then be linked to the material component on which it was

attached. Once the tag was associated, the workers would hit the “locate” button on the RFID/GPS

reader, and the component’s latitude and longitude is stored in the reader. The tag had been

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associated to the specific material component and now that specific material component was ready to

be tracked. When items arrived with barcode labels, the association process, after the tag had been

attached, was very simple, and completely automated. The association process takes approximately

10 seconds.

6.3.2 GPS mapping and RFID tag locations

Before the system was implemented, the lay-down yards throughout the site were geo-coded, mapped

and entered into a geographic information system (GIS), which divides the yards into their respective

coordinated grids. As Torrent and Caldas explained, GPS receivers can be set to transform collected

systems into a coordinate system. The default latitude and longitude degrees for a global system can

be transformed into a “local projected system” so that it “simplifies the implementation of the

localization mechanisms by providing coordinates in fundamental units of length, such as meters

(Torrent and Caldas, 2009). An image of the digital lay down yard on an office desktop easily

identifies the material and its location in the lay-down yard.

6.3.3 Tag item location with RFID/GPS system

When there are a large number of material items, attaching individual GPS receivers to each piece of

material has been deemed an infeasible option for the purposes of locating construction materials

(Torrent and Caldas, 2009). Therefore, the project in this study utilized six RFID reading devices that

were equipped with GPS receivers, and the material components were tagged with RFID tags. The

GPS receivers are able to determine their own location at any given time. The active RFID portion of

the reader could then be utilized with localization methods, which are algorithmic based location

projections based on strength of signal and reader location, as described by Torrent and Caldas, for

the projected locations of the RFID tagged components that were within reading range of the reader.

Periodic updates are made in order to update the projected locations of materials.

6.3.4 Automated locating process

With the RFID/GPS system in place, the goal is to make the material locating (flagging) process

much easier and faster. With the automated system in place, after the Engineer has developed a

material withdrawal request (MWR), the materials management office staff generates a pick ticket

packet which included a list of the required materials and each item’s specific yard and grid, as well

as a supplemental image, which would give the workers the approximate location of each component

within their respective grid, assigned by the GPS/RFID localization methods. The workers go to the

correct lay down yard and grid, and go approximately to where the printed map had indicated the

material’s location to be within that grid.

Once in the area, the workers utilize the RFID/GPS reader to narrow in and find the component. The

reader could pull up two different modes for finding the items. The map view utilizes the GPS

portion of the reader. The digital map of the yard can be displayed on the handheld screen and the

GPS receiver will show where the employee is standing, and the projected location of the material.

The employee’s positioning on the screen is represented by a blue dot, and the material component is

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represented by a red dot. Another method was to set the reader into what was referred to as the

Geiger counter mode. A Geiger counter is an instrument that can detect and measure radioactivity

(Iovine, 2000). The Geiger counter mode of the reader allows the worker to communicate only with

the specific tag that is desired. The Geiger counter can be utilized within 150ft proximity from the

tagged components. As the worker moves with the reader, the GPS receiver determines and gathers

information on the location of the reader. The RFID portion communicates with the desired tag, and

the reader utilizes localization methods based on the positions of the reader (gathered by GPS), and

the received strength of signal from the desired tag at those positions (gathered by RFID). A compass

pointed the employee in the direction of the tag with which the reader was communicating. When the

reader is within a couple of meters from the tag, the compass would change to a cross-hair and

display the words “WITHIN RANGE”.

6.3.5 Performance of the system

The performance of the technology was satisfactory and it was noted that there were very few

malfunctions. One issue of concern was whether or not the technology would perform in very cold

temperatures. They found that the system worked down to -26 degrees Fahrenheit. Also, it was

mentioned that at extreme temperatures below that mark, the readers were affected by the cold before

the tags, so workers would warm the readers by means such as holding the readers inside their coats.

Tags could easily be read through a couple of feet of snow.

Although the tags were durable, moving materials or placing heavy materials on top of each other can

sometimes damage the tags. It was proven that if the outer shell of the tag has been damaged, but the

internal battery and antenna device had not been affected, the tag maintained its readability function.

6.3.6 Results and future plans

Jim Rogers commented on the current standing of the automated system and the effects that

RFID/GPS have had on the project: “We used all the (RFID) tools, and the application of LEAN to

eliminate a wasteful flagging step. We now send the loading crew straight to the material rather than

having another pair of people go ahead to make sure they can find the material, flag or identify it with

colored ribbon, in order to optimize the loading crew’s time, and that of the crane. The quantified

savings were centered on eliminating the flaggers, although many other benefits are known, e.g.

schedule, supply chain risk, staging space savings.”

The RFID/GPS based system utilized on the project described in this case study will continue to be

used by the company for upcoming projects of similar type. Two new projects will utilize the same

technology are recently getting underway in Ohio and Illinois. In this case study, the automated

system was retrofitted to the existing materials already on site and in the lay down yards, however,

future applications will aspire to implement the system so that the materials will be tagged with RFID

before they arrive on the project site. When commenting on further developments of RFID based

solutions, and the processes that will be impacted and changed, Rogers noted: “The whole supply

chain, from engineering through procurement, field material management, construction, and some

selected components (that need maintenance) by the customer. We started with the greatest need,

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with a compelling business case, and we will build from there.” The future goals will be to track

different components throughout the entire supply chain, as well as while on site, and selected

components that will need maintenance in the future, could also remain tagged with RFID after

installation to facilitate easier identification for maintenance. To do this, it will require increased

cooperation and coordination with suppliers, customers, and others involved in the supply chain

process.

7. Conclusions

Although RFID technology solutions for the construction industry are still in the early stages of

development, case studies are showing that custom solutions can be proven beneficial for some

construction companies’ processes. Solid business cases for RFID based solutions that can be

uniformly applied across the construction industry remain to be seen. This may be in large part due

to the fact that each construction project will be unique to a certain degree, whether it is by size,

complexity, life-cycle, geographic location, etc. Also, depending on the size and structure of a

construction company, it may or may not be able to accommodate, and assign overseers for the

adoption of a new technological system. Those companies that remain curious and open minded

towards the technology will be more likely to realize potential benefits.

Materials management systems utilizing RFID technology may be further refined in the future if

manufacturers are encouraged to place the tags on the materials during the manufacturing process.

Materials ordered with RFID tags in place will truly be in line with the Lean construction process.

Another technology that may facilitate the transition from tracking field materials to in-place

materials is in the area of building information modelling (BIM). As more and more projects are

becoming BIM based, a natural progression will be to link the RFID solution to the BIM solution.

This would mitigate the problems currently encountered with reading tags of in-place materials and

the loss of data once a battery ceases to operate. If the owner receives an as-built model, the facilities

management process can eventually be streamlined. This is truly in line with the lean construction

philosophy.

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